1. Field of the Invention
The present invention relates to a method and apparatus for detecting an inferior container which is transparent or semitransparent.
2. Description of the Prior Art:
As a kind of the container, there is a sealed ampoule, which will be hereinafter described.
FIG. 1A shows an ampoule A in manufacturing of which: an ampoule blank "a" having an opening 2 at its top portion of a head 1 thereof as shown in FIG. 1B is filled with a solution or a solid substance fed thereto through the opening 2; and then the opening 2 is heated and melted to be sealed.
In the above case, in filling operation of the solutiion, there occurs many problems in which: the solution fed from a filling nozzle (not shown) is scattered; a front tip of the filling nozzle touches an inner wall of the head 1; or the blank "a" is splashed up to an upper inner wall of its head 1 with the filled solution due to a gas pressure produced in gas exchanging just before the ampoule is sealed in melted manner, which splash adhered to the inner wall of the head 1 is carbonized by heat applied thereto at a time of a melting/sealing operation of the blank "a" to become a scorch stuck to the inner wall. In addition to the above problems, there occur some other problems in which: a stain adheres to the inner wall of the blank "a"; a foreign matter is mixed into the solution; and so on. Consequently, a container having the above problems should be removed as an inferior one.
Hitherto, in detecting of such inferior container, a white board is placed behind the ampoule A which is subjected to an overhead lighting while the ampoule A is visually inspected by an operator. Therefore, such conventional detecting method has defects in that a detecting accuracy thereof varies widely due to differences in experience and sensitivity of the operator while the detecting accuracy itself is poor and an eye strain is caused in the operator. Further, the conventional detecting method has another defect in that an efficiency thereof is poor.
Consequently, the inventor of the present invention previously intended to eliminate such defects. For this purpose, it was proposed that a light source was disposed in a side of the ampoule throuth a light diffusion plate interposed therebetween, and a light beam from the light source through the diffusion plate was projected upon the side surface of the ampoule, of which light beam a light beam penetrated through the ampoule was received by a photo sensor to detect shadows produced by the scorch and the stain, which shadows are converted into an electric signal which is issued to a processing circuit so as to make it possible to detect the inferior container.
However, in such a conventional detecting apparatus, a shadow 4 produced by a flaw, bubble and the like (hereinafter referred to as the flaw and the like) all of which are produced in manufacturing process of the ampoule and are harmless in use is detected by the photo sensor 14 together with the shadow 3 as shown in FIG. 2. As a result, there is a defect that the ampoule A which is not the inferior one as to which there is no shadow 3 except the shadow 4 is removed in the conventional detecting method. Since an amount of such ampoules A reaches about 5 to 15% of the whole amount of the good ampoules, this results in an economic loss which is the defect of the conventional detecting method.